Electrical sockets



April 30, 1968 s. T. DEAKIN 3,381,261

ELECTRICAL SOCKETS Filed Sept. 1, 1965 STAN LEY TH OMAS DEAKIN Fla-501121014 g zlafi X paM MZ L ATTORNEYS United States Patent ()flice 3,381,261 Patented Apr. 30, 1968 3,381,261 ELECTRICAL SOCKETS Stanley Thomas Deakin, Farlington, England, assignor to Sealectro Limited, Farlington, England, a British company Filed Sept. 1, 1965, Ser. No. 484,347 Claims priority, application Great Britain, Sept. 3, 1964, 36,164/ 64 Claims. (Cl. 339248) ABSTRACT OF THE DISCLOSURE An electrical socket contact in the form of a metal tube having an intermediate longitudinal strip cut from the body of the tube having its ends joined to the tube, the strip being deformed into the tube to define a resilient obstruction within the tube to provide contact pressure on a contact pin insertable into the tube.

The invention relates to electric socket contacts of tubular form to receive a contact pin or wire and to a method of making such contacts.

The invention is concerned with contacts (hereinafter termed socket contacts of the above kind) which comprise a metal tube having two circumferentially separated longitudinal cuts in the wall of the tube and having a strip of metal left between the cuts which strip, at a point intermediate its ends (eg, at the centre of its length), is permanently deformed inwardly into the tube whereby a resilient obstruction is formed within the tube which obstruction is capable of being moved outwardly in respect of its position in the tube by a contact pin or wire inserted into the tube thereby providing resilient contact pressure on the pin or wire.

A disadvantage which arises in practice with sockets as just described is that the edges of the strip tend to rub on and bind against the edges of the remainder of the tube, especially if the cuts are slits made without removal of metal and extend radially through the walls of the tube.

An object of the invention is to provide a socket contact without the aforesaid disadvantage.

According .to the invention we provide a socket contact of the above characterised in that an electric socket contact comprising a metal tube having two circumferentially separated longitudinal cuts in the wall of the tube and having a strip of metal left between the cuts which strip, at a point intermediate its ends, is permanently deformed inwardly into the tube whereby a resilient obstruction is formed within the tube which obstruction is capable of being moved outwardly in respect of its position in the tube by a contact wire or pin inserted into the tube thereby providing resilient contact pressure on the pin or wire characterised in that the cuts provide, in the circumferen- .tial direction, clearance for the edges of the strip as it moves in and out.

The tube may be formed by rolling a strip blank about a longitudinal axis to bring the edges together or alternatively may comprise a solid drawn tube.

In one form of the invention the edges of the cuts are radial and the circumferential width of the cuts is such that the outer edges of the strip clear the inner edges of the body of the tube as the strip moves inwardly. In this case the strip is preferably deformed so that the centre of the width of the strip is moved radially inwardly.

In another form of the invention the edges of the cuts are radial, the strip is deformed in a direction parallel to the edge of one of the cuts and the width of the other cut is sufficient to permit the outer edge of the strip formed by this cut as the strip moves in and out to clear the inner edge of the body of the tube formed by the cut. In this case and when the tube is formed as described above by rolling a strip blank it is preferred that the said one cut is between the said edges which are brought together and the said other cut is provided through the wall of the tube adjacent one of the said edges. In this case the strip is preferably deformed so that the edge of the strip which is constituted by the edge of the blank is moved radially inwardly.

It is preferred that the end of the tube through which a contact wire or pin is to be inserted is bent outwardly to provide a smooth entry therein for the wire or pin. Such a construction is especially beneficial with contact wires or pins that have square ends.

The end of the tube opposite to that end through which a contact Wire or pin is to be inserted may be open or closed. In the latter case the socket may be passed through a hole in a printed circuit board, for example, and secured therein by dip soldering.

It is also preferred that when a contact wire or pin is inserted into the tube, the strip of metal left between the cuts remains within the compass of the tube and of its wall. This is especially beneficial when the wire or pin has a diameter substantially equal to the internal diameter of the tube.

It is further preferred that the inwardly deformed strip presents itself to the contact wire or pin as a resilient ob struction having a slowly increasing degree of obstruction thereby providing a high degree of pressure contact and requiring a low degree of insertion force.

In yet another form of the invention there are two cuts as aforesaid adjacent each end of the tube, in which each set of two cuts has a strip therebetween as aforesaid and in which each set of two outs provides, in the circumferential direction, clearance for the edges of the strip as it moves in and out.

The invention also provides a connector comprising a plurality of socket contacts described above enclosed in a common body of insulating material and separated from each other by the said insulating material.

By way of example, some specific constructions of socket in accordance with the invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 is a perspective view of the first construction of socket;

FIGURE 2 is a section along the line 2-2 of FIG- URE 1;

FIGURE 3 is a section along the line 3-3 in FIG- URE 1;

FIGURE 4 is a plan view of the blank from which the socket shown in FIGURE 1 is formed;

FIGURE 5 is a perspective view of the second construction of socket;

FIGURE 6 is a section along the line 6-6 in FIG- URE 5;

FIGURE 7 is a perspective view of the third construction of socket which socket is enclosed in a body of insulating material which is shown partly cut-away;

FIGURE 8 is a sectional view of the fourth construction of socket which socket is enclosed in a body of insulating material which is shown partly cut-away; and

FIGURE 9 is a perspective view of a connector comprising a multiplicity of sockets enclosed in a common body of insulating material.

With reference to FIGURE 4, the blank comprises a flat metal sheet 1 having a cut-out slot 2 which is located adjacent one of the longitudinal edges 3, 4 and extends parallel thereto. This blank 1 is used to form the construction of socket shown in FIGURES 1 to 3 by rolling up the blank into a tube such that the longitudinal edge 3 of the blank lies adjacent the other longitudinal edge 4, by forcing the strip of metal located between the slot 2 and the longitudinal edge 3, at its centre, inwardly in respect of the tube and by outwardly bending the extreme end 6 of the tube to form a smooth entry therein for a contact pin.

As can be seen clearly from FIGURE 3, the strip 5 is forced into the tube in such a manner that the edge 6 of the strip forming part of the longitudinal edge 3 moves radially into the tube, the strip of metal being stretched to produce a permanent deformation thereof. This step is carried out in the above manner so that a contact pin (shown in chain-lines in FIGURE 2) entering the socket will substantially only act on the said edge of the strip 5 and not on the whole width of the strip which latter action would tend to open the tube.

The length of the strip 5 is also chosen so that when bent inwardly it will present itself to the pin 15 entering the socket as a slowly increasing degree of resilient obstruction thereby providing a high degree of pressure contact on the pin and a low degree of insertion force.

Socket contacts in accordance with the invention are designed for use especially in applications which comprise a large number of miniature socket contacts very close together. In such a case the close proximity of the contacts require a contact which has an internal diameter only slightly in excess of the maximum diameter of the pin to be inserted therein and also a thin wall in order to minimise the intercapacitance between the contacts. Furthermore, the pins are frequently made of comparatively soft material and are often over 1 /2" long. For this reason, the low insertion force of the socket contacts of this invention is advantageous. In addition, the ends of the contact pins are normally provided with square ends and thus the afore-mentioned provision for smooth entry for the pin into the socket is also advantageous.

With further regard to FIGURE 2, the expanded position of the deformed strip 5', after the pin 15 has been forced into the socket, is shown in chain-lines. It will be seen that the strip has still remained inside the compass of the tube and its wall. This is beneficial since any projection of the strip outside the tube would increase the intercapacitance between contacts and also increase the chance of flashover.

The slot 2 may be replaced by a slit but it is evident that the slot or slit must be of sufiicient width such that the strip 5 may be forced inwardly as aforesaid and such that no grating of the strip and the remainder of the tube will take place on expansion of the strip by a contact pin inserted into the socket.

The distance to which the strip 5 is forced into the tube depends on the distance required to produce permanent deformation of the strip and also the size range of contact pins that is required for a particular socket. We have found it best to force the strip into the tube until the innermost point of the edge 6 of the strip is just short of the longitudinal axis of the tube (i.e. to the position shown in FIGURES 2 and 3).

The second construction of socket (see FIGURES 5 and 6) is made from a hard drawn tube 10. The tube is provided with two slots, 11, 12, which are spaced apart, extend parallel to the longitudinal axis of the tube and define between them a narrow strip of metal 13 corresponding to the strip 5 of the socket shown in FIG- URES 1 to 4. This strip is forced inwardly with respect to the tube, but in this case either the longitudinal edge 14 of the strip 13 of the centre point of the strip 13 may be moved radially into the tube.

In a similar manner to that of the first form of socket, one of the slots 11, 12 may be replaced by a slit provided that the strip 13 may still be forced inwardly of the tube in the direction and to the extent desired, without interference between the edges of the strip and the remainder of the tube.

With regard to FIGURE 7, the third construction of socket is identical to the first construction of socket except that the end 16 of the tube opposite to that end through which the pin is inserted is closed. The closure of this end necessitates the pin being cut to length but allows the contact to pass through a hole in a printed circuit board, for example, and to be secured therein by dip soldering.

The fourth construction of socket contact (see FIG- URE 8) comprises a pair of identical sockets formed one at either end of a length of hard drawn tube, the sockets being identical to the sockets described with reference to FIGURES 5 and 6. It is preferred, however, as shown in FIGURE 8 that the deformed strips are diametrically opposed to each other. It is also to be appreciated that the tube could be rolled from a strip blank and the sockets constructed in like manner to those described above with reference to FIGURES 1 to 4.

Both the constructions of socket shown in FIGURES 7 and 8 are also mounted in an insulating body 17, which body may be made of Telion or polypropylene, for example. This principle may be extended by enclosing a plurality of sockets in a common casing of insulating material (see FIGURE 9) to form an electrical connector, the casing being provided with a through hole 18 for securing the casing in a desired position and a plurality of round holes 19 for the sockets, the hole 19 being counterbered at the ends through which the contact pins are to be inserted to recess the sockets therein.

I claim:

1. An electrical socket contact adapted to have a contact pin inserted therein, said socket contact comprising a metal tube having two circumferentially separated longitudinally extending cuts in the wall of the tube defining a strip of metal left between said cuts, said strip of metal being joined at each end to the wall of the tube and said strip having two edges, said two edges of the strip being radial, said strip at a point intermediate its ends being permanently deformed inwardly into the tube in a direction parallel to one of said two edges of said strip, positioning said one edge nearer to the axis of the tube than the other edge, whereby upon the insertion of a contact pin into the tube the contact pin acts upon said one edge of the strip rather than upon the whole width of the strip, and the circumferential width of the cut adjacent to said other edge of the strip being sufiicient to permit said other edge to clear the wall of the tube as the deformed strip moves out or in response to insertion and withdrawal of a contact pin.

2. An electrical socket contact adapted to have a contact pin inserted therein as claimed in claim 1 wherein said metal tube is formed by rolling a strip blank about a longitudinal axis to bring the edges of the blank together and in which one of said longitudinally extending cuts in the wall of said tube is between said edges of the blank which are brought together, the other longitudinally extending cut being provided through the wall of the tube adjacent to one of said edges of the blank which have been brought together.

3. An electrical socket contact adapted to have a contact pin inserted therein as claimed in claim 2, in which said one edge of the strip which is positioned nearer to the axis of the tube is constituted by an intermediate portion of the edge of the blank displaced radially inwardly.

4. An electrical socket contact adapted to have a contact pin inserted therein, said socket contact comprising a fiat metal sheet blank having first and second longitudinal edges, a cut out slot extending parallel to the first of said longitudinal edges, said slot being located adjacent to and spaced slightly from said first longitudinal edge to define a strip of metal between said first edge and said slot, said strip of metal being connected at both ends to the body of the sheet blank, said sheet blank being rolled into a tube with said edge adjacent to said second edge of the blank for defining a tubular socket, said strip of metal at a point intermediate its ends being permanently deformed inwardly toward the axis of said tubular socket in a direction such that said first edge of said strip forming part of the longitudinal edge of the sheet blank is displaced radially into said tubular socket toward the axis of the tube with said first edge of the strip being positioned nearer the axis than the opposite edge of the strip and with said strip of metal having a permanent deformation, and said cut out slot having a sufiicient width to permit the opposite edge of the strip to clear the inner edge of the tube extending along said cut as the strip is moved by insertion of a contact pin into the socket.

5. A pair of electrical socket contacts each formed at either end of a metal tube and each socket contact being adapted to have a contact pin inserted therein, said pair of socket contacts comprising a metal tube having adjacent each of its ends a pair of circumferentially separated longitudinally extending cuts in its wall, each pair of cuts defining a strip of metal left between them, one of said strips being adjacent to one end of the tube, the other strip being adjacent to the other end of the tube, each of said strips being joined to the wall of the tube at both ends of the strip, said strips being positioned 25 on diametrically opposite ends of the axis of the tube,

and each of said strips being permanently deformed inwardly into the tube in a direction toward the axis of the tube positioning a first edge of each of said strips nearer the axis of the tube than its second edge, and said first edges of the respective strips being positioned to make edge contact with respective contact pins inserted into the respective ends of the metal tube.

References Cited UNITED STATES PATENTS 2,422,265 6/1947 Squires 339-258 2,563,761 8/1951 Uline 339-256 2,711,524 6/1955 Beaver 339-256 3,040,288 6/ 1962 Edlen et a1. 339-256 3,112,149 11/1963 Bachman 339-258 3,206,717 9/1965 Brown et al. 339-198 3,208,027 9/ 1965 Johnson 339-258 3,218,606 11/1965 Schultz 339-256 FOREIGN PATENTS 16,837 1904 Great Britain. 336,612 10/1930 Great Britain.

MARVIN A. CHAMPION, Primary Examiner.

PERRY TEITELBAUM, Assistant Examiner. 

